Mesh&More, the successor of Vgrid, is a hybrid 3D mesh generator for medical image data.

The Mesh&More mesh generator

Mesh&More is a
dimension-independent mesh generator
based on spacetrees (generalised octrees).
That is, Mesh&More works on
a volume-based geometry representation (such as medical image data),
in contrast to most other mesh generators
which work on a surface-based geometry.

A volume-oriented representation means
that for every point in space an efficient query for properties is possible.
The most basic case is whether that point is part of the geometry or not.
Slightly more advanced is a query which (sub-)region the point lies in,
for instance defined by material type in a segmented medical image.
Subregions are problematic for most surface based representations
which typically expect a single region bounded by a smooth surface
(mathematically speaking, they expect the region surface to be a sufficiently well-behaved manifold).
Thus, a volume-oriented geometry description is a more natural choice
for meshing volumetric data sets
which have no readily available surface-based representation,
in particular not one which is smooth and manifold.
Representation of internal material boundaries is built into the volumetric representation
almost by definition
(although this does not mean
it is easy to generate good meshes for each configuration of internal boundaries).
Furthermore, it is (in principle) straightforward
to let local properties of the space
guide the mesh generation process
(type of elements, resolution, algorithm).
Again, this does not mean it is always easy to generate good meshes for each combination.

Mesh&More builds on the basic concepts of
Vgrid;
the software however was developed completely from scratch using
generic programming.
The sources are available under the GPL from
this page.